Cliff Mass Weather Blog: Snow Removal Report Card and Some Suggestions

But what actually was maddening about the METRO folks is their determination to close off the bustracker software EXACTLY WHEN WE Required IT!They receive a lame excuse about the bustracker locations having errors when the bus go off the regular routes, but this wee little sense.For about of the snow routes useful information IS provided.And they certainly could change the bustracker website to provide what information IS there.

hen the buses pass certain locations.The accuracy is that Subway has been very easy in passing to a GPS tracking system and let never given sufficient emphasis to giving its patrons good information about where the buses are located.They could be doing much better still with their current old-fashioned location system.The ForecastersYou don't ask me to be critical of my own profession, do you?The National Weather Service did almost as easily as the technology allows-a figure that was just enough to provide warning of possible trouble.The day before they were going 1-3 inches, mainly in the afternoon as a coastal low moved south of the Olympics.Basically, they closely followed their main high-resolution model (the NAM, WRF-NMM).If you read their forecast carefully, they were just going for some flurries or light stuff in the morning, but it turned out to be substantially more (1-2 inches in places).The coastal low was more intense that expected by their exemplar and they had to up the forecast snow amounts during the day.The NWSwas correct about cold air coming in after that day.I own to admit, my forecast was not as good regarding snow the dark before.I depend heavily on the UW high resolution system, which normally is master to the NWS NAM modelfor a bit of technical reasons I won't go into here.But this place was strange and the NAM was best that morning (I will get a future blog telling why and steps we are taking to fix it).Essentially, the UW system took the coastal low further south and the snow shield only extended to south Seattle.The UW system recovered Monday morning with a real good forecast-in sight of time to contend with the afternoon threat.Play by Play AnalysisOn Monday morning the temperatures were near freezing as the start beat of snow moved in.Since it had not been that cold and this was early in the season (remember it was 74F a few weeks before!), the land and road surfaces in liaison with it were relatively warm.Even the elevated structures (e.g. the Alaskan Way viaduct) hadn't cooled below freezing.So when the snow started, particularly with generous amounts of deicer SDOT had spread around, the roads were fine.The morning commute had very little problems.People got into play and school.I even biked in with no hassles on the Burke Gilman Trail.So far so good.But so the problems began.The low center on the north coast deepened more rapidly then expected and moved across the southern flanks of the Olympics (see satellite picture below)As the low moved south, it produced moderate, mild southwesterly flow that moved north to meet northerly flow pushing south down the Sound (the north course was accelerating toward the heavy pressure over the south Sound).The converging air streams resulted upward movement and bands of snow.But at the same time the northward course brought colder and colder air over Seattle starting about 3-4 PM.Here are the temperature and wind plots from the top of my building at the UW that day.Temps were between 28 and 30F until just after 3 PM and then temperatures started to fall quickly.At the same time the winds started to get much stronger and gusty (see figure).Strong winds are significant because they allow much more effective removal of passion from the surface.It is alike a fan blowing cold air over the ground.much more good for cooling.And now it all came together.The deicer put on earlier was increasingly diluted by the larger volumes of snow falling into it until it became of marginal value.The air temperatures were rapidly dropping and the warm winds enhanced cooling.What would ice up first?You know what.the elevated roadways which did not enjoy heat conduction from the relatively warm ground below.The Alaskan Way viaduct iced.The West Seattle Bridge.And since much of I5 is elevated, it glazed over quickly as well.Icemageddon.Traffic locked up on major roadways. Plow and sanders couldn't get to where they were needed.Trucks and buses got into trouble.And the rest was history.What to DoWhat I am near to utter is opinion.and I am probably missing key points.but I will go ahead anyway.First, although weather forecasts are getting better, any new systemfor dealing with snow has to be rich enough not to look on the forecasts being set in the timing or quantity of snow.It will be 5-10 days earlier the 12h forecasts are dependable enough for such work.We are rather right in telling you if the stale and winds will come.Or telling a threat.But acquiring the precise number and dispersion of snow even 6-12 hr out is not here yet.The Nov 22 forecast by my colleagues in the NWS were far better than what they could get done 10 days ago.It was near enough to alarm the metropolis and various DOT agencies, and to let the general public knowthat something seriouswas possible.Certainly KING TV and other stations knew-they were hyping it up like mad the dark before.Jim Forman was getting his famous parka pressed and readied.But if the forecasts are not perfect, what is required is good nowcasting-a terminus in my field which means examining current observations carefully and intelligently extrapolating them into the future.There are 50-100 weather stations reporting in actual time in the city.With this information, one could see just what the temperatures are and lead the changes.As soon as the warm winds and colder air started to fight in, it was time to get out there getting rid of coke on the roadways and hit them with dozens of salt.Using the weather radar and temperature information it is also possible to decide the snowfall patterns over the city (this will get still better next year with the NWS updating of all local weather radars to dual-polarization and the accession of the new coastal radar).With the data about how much snow is on the ground, where it is falling, and how temperatures are changing, SDOT and WSDOT should be capable to do their work far more effectively.particularly in getting ahead of the storm.A package system could be created to tear all this information together.we could claim it SNOWWATCH.Furthermore, the city needs someone with meteorological training watching all the observations in actual time during these events.Once the ice forms, you are in trouble.The key is toknow when c is falling and to plow as lots of it as possible off the roadstead and then hit it with salt (my friends in the business suggested prewetted salt when temps are cold).If the snow keeps up, you get to repeat.Now at around 3 PM it was absolved from the weather observations that bad things were nigh to happen.The surface chart showed northerly winds start to clean up and cold air moving in from the north (see plot).The radar showed snow over the region (see plot). Click for big version.

3PM surface observations

Conclusion:it was almost to get colder, winds would increase and the scourge of ice was around to increase rapidly.At this point, all equipment required to be used on elevated structures immediately, and when those were clear and salted (solid not brine), then the other roads could be dealt with.Metro needed to draw all their articulated buses off the elevated roadways at this point.in fact, they should have replaced with with the non-articulated fleet hours before.Rapid deployment when the conditions was clearly going to change seems to me the only viable option.Question:Do any of the roadway surfaces in the city have real-time temperature measurements?If not, shouldn't this be fixed immediately?In summary:I am suggesting a compounding of the intensive use of all observational assets to allow a real-time aspect of the conditions and road conditions about the city, and the flexibility to use the limited assets of the metropolis and WSDOT to hit the big threats first, guided by these observations.The flow state-of-the-art of weather forecasts are right enough to make a heads up, but not adept enough now to guide hour by hour actions.